In configurations in which members slide relative to each other or members (connecting members) which connect by sliding relative to a contact surface with another member, a film is typically formed covering the sliding surfaces of the members. Examples of such members include exterior finishing materials for optical devices or the like. Examples of such connecting members include so-called bayonet mounts (below, simply “mounts”) provided on the camera body side and lens side of camera systems in which different lens units can be interchangeably attached to and detached from the camera body. Such mounts generally include a base material made from brass and a conductive, protective film made from metallic chromium and formed on the surface of the base material.
Recently, use of conductive carbon films made from a metal-doped tetrahedral amorphous carbon material in place of the conventional metallic chromium films has been proposed (WO 2011/138967).